The present invention relates to containers for unexposed photographic materials, and more particularly to improvements in cassettes for film units, namely, for assemblies including several sheets of photographic material. As a rule, a film unit comprises a negative sheet and a positive sheet which overlaps or is overlapped by the negative sheet.
It is already known to provide a cassette for a stack of film units with an aperture which admits light during exposure of the foremost film unit to scene light. It is also known to connect each film unit with a flexible withdrawing element which serves to effect extraction of an exposed film unit from the housing of a cassette. The withdrawing elements extend outwardly through an opening of the housing.
German Pat. No. 471,213 discloses a cassette wherein a freshly exposed film unit can be withdrawn into a compartment which is located behind the stack of film units. The compartment receives successive exposed film units and is accessible only upon exposure of the last film unit of the entire stack. This is impractical in many instances, e.g., when it is necessary to immediately develop an enlarged image of an original in a photographic copying machine.
German Pat. No. 1,214,539 discloses a cassette for use in an instant-picture camera. The film units (each of which consists of two sheets) are connected with flexible withdrawing elements projecting outwardly through a lateral slot-shaped opening of the housing of the cassette. The withdrawing elements extend through the nip of two rollers which serve to rupture a pod containing a developing fluid which is thereupon spread between the sheets of the respective unit so as to insure that the freshly exposed image is developed in automatic response to extraction of the corresponding withdrawing element. Cassettes of the just outlined character are not suited for use in apparatus or machines wherein the freshly exposed film units should or must be developed at a location other than in the interior of or during withdrawal from the housing of a cassette.